Workcat: cute desktop cat, no window closing

Reworks the example into a pure desktop-pet: the cat wanders, sits, grooms,
stretches, dashes and naps, reacts to petting and dragging, and follows the
cursor with its eyes. The window-scanning and Accessibility code is gone.

The cat is drawn from rounded primitives plus Shape paths in a fixed 100x90
design space, so it scales cleanly to any size.

Linux/X11 is the primary target: the tray is optional, Wayland gets a warning,
and WORKCAT_X11_BYPASS / WORKCAT_OPAQUE cover uncooperative window managers.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/platforminfo.h

@@ -0,0 +1,39 @@
+#pragma once
+
+#include <QObject>
+#include <QQmlEngine>
+#include <QString>
+
+// Small facts about the host that QML needs in order to pick window flags.
+class PlatformInfo : public QObject
+{
+    Q_OBJECT
+    QML_NAMED_ELEMENT(Platform)
+    QML_SINGLETON
+
+    Q_PROPERTY(QString name READ name CONSTANT)
+    Q_PROPERTY(bool isX11 READ isX11 CONSTANT)
+    Q_PROPERTY(bool isWayland READ isWayland CONSTANT)
+    Q_PROPERTY(bool bypassWindowManager READ bypassWindowManager CONSTANT)
+    Q_PROPERTY(bool opaqueBackground READ opaqueBackground CONSTANT)
+
+public:
+    explicit PlatformInfo(QObject *parent = nullptr);
+
+    QString name() const { return m_name; }
+    bool isX11() const { return m_name == QLatin1String("xcb"); }
+    bool isWayland() const { return m_name.startsWith(QLatin1String("wayland")); }
+
+    // WORKCAT_X11_BYPASS=1 turns the cat into an override-redirect window.
+    // Useful on window managers that refuse to keep a Qt::Tool window on top.
+    bool bypassWindowManager() const { return m_bypass; }
+
+    // WORKCAT_OPAQUE=1 paints a solid background instead of relying on a
+    // compositor. Without compositing X11 renders transparency as black.
+    bool opaqueBackground() const { return m_opaque; }
+
+private:
+    QString m_name;
+    bool m_bypass = false;
+    bool m_opaque = false;
+};